metal enclosures

the member thuppu built a sub enclosure out of metal (and perhaps some wood). go to page 4 in the DIY gallery for pics of it to give you an idea. finished work was very nice and i'm considering a similar design myself, but out of sonotube.

Would it not be much more expensive to build a metal enclosure, as opposed to one out of plywood or MDF?

Im not sure, though one thing I wonder is the noise the material itself makes. You can tap on a hunk of MDF with your knuckles and get a dull thud sound. Tapping your knunckes on metal, you get an echoing bang/twang/clank sound.

Its been awhile since Ive ordered steel sheet-metal, but I beleive it costs me $75.00 for a 6x8 (or was it 6x10? 4x8??? I forget) sheet of 1/8th inch thick. I suppose if you covered one side of it with some deadening material like rubber, it would be fine.

The thing about the snail design, is its a cylinder. Correct me if im wrong, but pressurizing a cylinder, you mostly just get a force that streches the metal. In a cube, you get a force that will try and bend the sides outwards. I think the word for it is tensile strength. I can give you a 1/4" thick steel rod 1 foot long, most people shouldnt have too much trouble bending it in half, with just two hands and possibly a vice, if they are using good steel. But I dont beleive anyone could strech that 1/4" thick steel rod by hand, considering towing chains are about that thick.

Im sure you could build a snail design out of steel sheet metal for fairly cheap, the neat thing about metal, you can bend it. Though, it takes a lot of skill to do things correctly with metal, especially rolling flat peices into perfect cylinders, and welding it all together without warping anything.

Yeah, I didn't even mention the fact that the metal would be far more resonant than MDF or ply.

A MDF - aluminum - MDF sandwich enclosure might be nice, though I don't think the strength of a double walled MDF enclosure would be much of an issue in the first place

The question: Is steel at X thickness resonant at subwoofer frequencies. Most materials are resonant at some frequency... the goal is to create an enclosure design that isn't resonant at the frequencies being reproduced. Also, think about having to move the sub around (plan for some solution).

You could make a subwoofer enclosure out of 3/4" stainless plate, make nice heli-arc welds and turn the enclosure finish with a wire wheel, you know, like the nose of the Spirit of St. Louis. To get it ringing you'd have to slap it with a 12 pound beater, not a likely happening, no driver would excite that much mass. Especially if you braced it inside with 2" channels.

Weld a lifting lugs on it and move it with a comealong . Or tap it for eyebolts, shouldered ones please.


Tom Brennan

retiree Boilermakers Local 1, Chicago

That sounds great, but honestly, wouldn't that cost big $$$$? Metal plate, especially 3/4" stainless steel, is not cheap...but you know that.

3/4"? You could back over that with a dump truck and not dent it

"wouldn't that cost big $$$$? Metal plate, especially 3/4" stainless steel, is not cheap"


Well let's build it from mild steel, that's easier to work with anyway.

You could make a really stiff/dead enclosure if you bonded sheet metal to both sides of 1" rigid foam insulation that you can get at Home Depot; I think it's like $20 for a 4'x8' sheet.

zk-----To be serious I think your best shot with a metal speaker would be a sphere. Diffraction would be less of a problem and standing waves inside the cabinet would be minimized (though that's rarely a concern with normal cabinets anyway). And a sphere would be stiff, probably the best shape for light metal.

This is what makes AVS Forum fun - the different perspectives on things. To Tom Brennan metal work is easy - to me; it's way out of my league!!

This looks to be a good thread.

Why not look into some spherical designs, like Tom mentioned. Like this: http://www.avsforum.com/avs-vb/showt...&&#post7259357

I wonder if you could make a decent two-way speaker using spheres like that...

What's your budget? Are you trying to do a full-range speaker, or just a subwoofer?

I think that the best use of steel in a speaker within a reasonable budget would be using a beer keg as a sealed enclosure. You could put a 12" woofer in each end, or even a single 15" driver. The benefit is that the steel would withstand huge pressures without flexing. You could use a linkwitz transform circuit, and with enough power you could get a volume of bass from a small enclosure. Depending on drivers, you could even put a 15" on each end.

I think it would look cool if you set these up horizonally on stands like Taiko drums.

A beer keg enclosure?! Why didn't I think of that..hah.

I've written about it on different forums in the past. The only time I've seen a photo of somebody who did something similar was at a bar in Japan where they put a Lowther (or other similar exotic "full range" driver on the end of a wooden keg).

Please keep in mind that it might not be legal to keep a keg after emptying it- the keg might still be property of the brewery. If you're resourceful, you could track down a company that makes or repairs kegs, and get them to sell you a keg with a broken valve.

If you're not using it for a small sealed enclosure for extreme internal pressures, you're not gaining much. You'll want to coat the inside of the keg with some sort of foam or goo to prevent the metal walls from being excited by other speakers in the system. You'll also want to keep your lowpass below 80hz or so to prevent internal standing waves.

Uh..of course. Why would someone use a keg they rented to build a subwoofer?

I was joking, anyway. I doubt I would ever do something like that. Maybe just for kicks, but not for a serious solution. It would be neat in a dorm room though.

You can get the box smaller with metall for example.
Here is my old metal-mini-sub(XLS 10") thats material thickness is only 8mm:

What about a metal cylinder? Say from 22 gauge metal and build it like you would a sonosub? Would this work alright? I'm in the HVAC business and it just crawls all over me that if you can keep the right driver from producing unwanted resonance...this could be very doable.

Would this totally throw the sonosub.exe program off the tracks If used it to design only using metal instead of a tube?

Krell uses alu construction for the upscale speakers and the dual opposed sub ( MRS ).

Alloys can form a shell much stronger than anything you can build out of MDF. MDF is a very dense CARDBOARD that is all it is. No long fibers and it breaks nasty ,I tried many experiments and MDF is far from great.

It is very very cheap(inexpensive) and anyone with half a talent can build very good looking cabinets,as MDF is easy easy to work with. Save for the nasty dust.

To seriously build alloy cabinets you would require a metal working shop with tooling your HomeDepot can dream of. Plus some CNC machines.Unless building something where little bending,forming,groving is needed.

Non ferrous alloys can be incredibly strong and inert,problem is cost and the level of competence to work them((yeah tooling,ahem CNC machines,who owns one ).

My two cents

Thuppu ,nice work ! Actually,great work,I can see a tank like box,quite a few weld joints on the brace.Good job.